1. Field of the Invention
The present invention concerns an anti-dazzling and electrostatic charge preventive transparent coating material, which is applied to the external surface of a video display or CRT to prevent dazzling and electrostatic charging.
Generally, the screen of a CRT or LCD is made of an insulating transparent material with a high surface resistance such as glass or reinforced plastic that accumulated, electrostatic charges, so that foreign materials such as dusts in the atmosphere are adhere to the screen surface, thereby deteriorating the visual quality. Moreover, the user may be subjected to an electrical shock. Additionally, if the LCD substrate is electrostatically charged, a misoperation may occur so that the segment not supplied with a driving voltage is driven.
Meanwhile, the surface of the screen is generally flat, and directly reflects the external light, so that it tends to make it difficult to distinctly view the images displayed on the screen. This tendency becomes more serious as the external light becomes stronger. In a place of high illumination, it is impossible to distinctly view images on the display having low brightness such as LCD and CRT. Hence, long time use of such a display causes fatigue the user's eyes to be.
Conventionally, in order to solve the external light reflecting problems as described above, a coating material mainly comprising a polymer containing silica is applied to the external surface of a video display by spraying, thereby roughening it so as to effect diffused reflection (refer to U.S. Pat. No. 3,689,312 and Japanese Patent Application Laid-Open No. sho 61-118,932), or alcohol or water solution mainly comprising silicate is applied to the external surface of a video display to form a continuous coating, which is mechanically rubbed, to produce a roughened effect reflection (Japanese Patent Application No. sho 63-138,724.
In addition, the electrostatic charge problem as described is solved by applying one of the following compositions to the external surface of the video display:
(A) mixture of fluorinated water repellant, chlorinated surfactant and alcohol (refer to Japanese Patent Application Laid-Open No. sho 60-156,783);
(B) silicon alcoholate to form a SiO2 film, which is grounded (refer to Japanese Patent Application Laid-Open No. sho 63-158,733); and
(C) alcoholic silicasol obtained by hydrolyzing a hydrolytic silicate, with an addition of metallic compound (refer to Japanese Patent Application Laid-Open No. sho 61-16452).
Further, if the electrostatic charge preventive coating material of the Japanese Patent Application Laid-Open No. sho 61-16452 is sprayed on the screen so as to roughen the external surface of a wide screen to effect diffused reflection, it is hard to uniformly roughen the whole surface of the screen. Moreover, since the electrostatic charge preventive effect of this coating material is caused by the moisture in the atmosphere absorbed by the material, it is hard to achieve in a low moisture environment, and when the water resistance of the material is considerably low.
In Japanese Patent Application Laid-Open No. sho 60-221937, there is disclosed a CRT whose external glass surface is roughened and coated with 1-valence alcohol or ester colloidal solution of SiCl4. In this case, preparation of the roughened surface to effect diffused reflection and application of the coating material to prevent the electrostatic charge are performed separately from each other, thereby complicating the process, increasing the cost of the effect of diffused reflection and reducing the electrostatic charge prevention.
According to the method disclosed in Japanese Patent Application Laid-Open No. sho 63-160131, the solution of polyalky siloxane is applied to the external surface of the screen, subjected to condensation, so that the silanol(Si-OH) residing on the surface reacts with the moisture in the atmosphere creating conductivity, thereby preventing the electrostatic charge. In this case, the conductivity depends level of moisture in the atmosphere, and therefore, the desired reduction of the electrostatic charge would not be achieved in a dry environment.
Referring to P270-273, SID 89 DIGEST, in order to simultaneously achieve the effects of diffused reflection and electrostatic charge prevention, an electrostatic charge preventive composition is evenly applied to the external screen surface, which is again coated with a composition containing particulates to effect diffused reflection. In this case, the complicated process not only increases the production cost, but also requires particulate production and dispersion apparatuses in order to produce the particulate dispersed composition. Further, additives such as a dispersion agent is required, increasing the production cost of the composition.